Blinded morphometric assessment of colitis after oral treatment with 2.5% DSS for 7 days in WT mice (n = 7), WT⇒WT, WT⇒iNOS−/−, iNOS−/−⇒WT bone marrow chimeric mice (n = 8 per group), and iNOS−/− mice (n = 7), based on morphometric measurements described in Materials and Methods. Showing percentage of surface ulcerated. Mean ± SEM. #P < 0.05 versus WT, and *P < 0.05 versus WT⇒WT.